Trip unit mechanism



9,1956 G. E. GAUTHIER ETAL 3,265,836

TRIP UNIT MECHANISM Filed Jan. 25, 1965 INVENTOR5 660E055 Gama/12,

/mmss E H0550, (/R. BY WM United States Patent 3,265,836 TRIP UNIT MECHANISM George E. Gauthier, Plainvilie, and Charles F. Hohson, Jr., Southington, Conn., assignors to General Electric'Company, a corporation of New York Filed Jan. 25, 1965, Ser. No. 427,718 7 Claims. (Cl. 200-116) This invention relates to circuit breakers and more particularly to circuit breakers of the multipole type having a trip unit of the collapsible toggle type as an operative portion of its latching mechanism.

Circuit breakers of the type referred to frequently have trip units which are mounted in the main insulating casing of a multipole circuit breaker to engage the main operating mechanism of the circuit breaker for actuation thereof and to cause disengagement of the main current carrying contacts of the circuit breaker upon the flow of overload currents of predetermined amplitude through the circuit breaker. Such multipole circuit breakers may be rated for current carrying capacities of 600 to 1200 amperes, for example. Additionally, a circuit breaker of this type usually has a reciprocally operable handle extending externally from its insulating casing for manual operation to disengage the main current carrying contacts of the circuit breaker. However, such manual operation and disengagement of the main current carrying contacts of the circuit breaker does not release the latching mechanism of the trip unit from engagement with the main operating mechanism of the circuit breaker. Accordingly, if it is desirable or necessary to install a replacement trip unit in the circuit breaker, means must be provided to externally trip the release mechanism of the trip unit which is to be removed from the circuit breaker to thereby disengage its latchingportion from the main operating mechanism of the circuit breaker.

The present invention provides such a means which additionally functions as a stop for the collapsible toggle links of the latching mechanism of the trip unit and is conceived to incorporate an adjustable means to adjust the disposition of the collapsible toggle linkage in its straightened or set position.

Accordingly, it is a principlal object of the present invention to provide an improved external manually operable means for tripping the trip unit of a multipole circuit breaker.

Another object of the present invention is to provide such a means which also functions as an adjustable stop for the collapsible toggle links of the latching mechanism of such a trip unit.

A further object of the present invention is to provide a combined external manually operable means for collapsing the toggle links of the latching mechanism of a trip unit together with an adjustable stop for such spring biased toggle links which is simple, inexpensive and reliable in its operation, as well as adaptable to a broad variety of circuit breaker trip units of the type described.

The invention in one form comprises a trip unit adapted for removable mounting in a multipole circuit breaker and including a casing enclosing the trip unit and having at least one aperture. The latching mechanism of the trip unit includes a tripping assembly mounted on the trip unit and having toggle linkage disposed and supported to be movable between straightened and collapsible positions. The toggle links are spring biased to straightened position extending through the aperture for maintaining a tripping member in restraining engagement with a releasable means of the main operating portion of the circuit breaker. At least one current responsive means is included in the trip unit and is adaptedand positioned to cause the collapse of the toggle linkage upon the flow "ice fix the adjustable disposition of the toggle linkage in its straightened position.

In its preferred embodiment, the externally operable lever for tripping the trip unit carries such adjustable means between its pivot point and its point of engagement with the toggle linkage so as to adjustably bear upon an adjacent member of the latching mechanism of the trip unit.

These and other additional features and objects of the invention will be more fully understood from the following detailed description together with the illustrations of the accompanying drawings and the scope of the invention will be pointed out in the appended claims.

In the drawings:

FIGURE 1 is a side elevational view of a portion of the improved unit of the present invention together with portions of the main operating mechanism of a multipole circuit breaker with which it may be employed.

FIGURE 2 is a side elevation-a1 view of the improved incorporated therein; and

FIGURE 3 is a side elevational view comparable to the illustration of FIGURE 1 and illustrating the operation of the manual release of the present invention.

Referring now to FIGURE 1, there is shown a contact arm 10 of a multipole circuit breaker including thereon a contact cross-armf1 1 which is in rigid and common connection to the remaining of the plurality of pivoted contact arms such as the one arm shown at 10. Those skilled in the art will appreciate that multipole circuit breakers of the type referred to will usually include a contact arm such as shown at 10 in each of its pole sections and carrying one or more movable contacts which are adapted and arranged to be brought into electrical engagement with stationary contacts and to be disengaged therefrom to interrupt the flow of overload currents of predetermined amplitude. A releasable member 112 of the main operating mechanism of the electric circuit breaker is shown as having a latch portion 12a in latched engagement with a primary latch 13 which is pivotally mounted and supported by appropriate means carried by the main insulating casing of the circuit breaker such as shown at 14. The primary latch 13 is spring biased. so as to be urged toward pivotal movement clockwise about its pivotal support 14. When the circuit breaker is in its latched condition, i.e., the main operating mechanism of the circuit breaker is in latched engagement with the trip unit, a tripping member 15 of the latching mechanism of the trip unit is positioned to restrainingly engage and position the primary latch member 13 to maintain its latched engagement with the latch portion 12a of the releasable member 1'2 of the main operating mechanism of the circuit breaker. The tripping member 15 is supported by a link 16 which in turn is carried on a pivotal support 17 extending from a boss 18 of casing 19 of the trip unit. The tripping member 15 may take the form of a rotatable bar to minimize frictional forces in its engagement and disengagement with the primary latch member 13. The tripping member 15 is supported and disposed so as to be maintained in a position to Addirestrainingly engage the primary latch member 13 by a pair of toggle links and 21 as shown in their straightened position. The link 21 is movable about a fixed pivotal support 23 and the links 20 and 21 are collapsible about a common point of linkage pin .22. Toggle link 20 has an L-shaped extension 20a which establishes and fixes the straightened disposition of the toggle links 20 and 2/1 in a manner which will be explained and more fully understood hereinafter. A secondary latch 24 is mounted on the same fixed pivot support 23 as is the toggle link 21 for pivotal movement thereabout independently of the toggle link 21. The secondary latch 24 is connected through a toggle link 25 to a pin means 26 in member 27 which is pivotally supported on a fixed support extending from the boss 29 on the trip unit case 19. Member 27 is spring biased by a spring 30 so as to be urged for movement in a clockwise direction, thus exerting through toggle link 25 a spring bias force upon secondary latch 24 urging it for movement in a counterclockwise direction about its pivotal support 23. Such counterclockwise movement of the secondary latch 24, is, however, normally prevented by a trip bar 3 1 which has a suitable latching means such as the half-round portion 31a, as illustrated in FIGURE 1. Accordingly, upon the operation of current responsive means within the trip unit, which may be thermally or magnetically sensitive or both, the trip bar 31 is rotated in a counterclockwise direction slidingly disengaging the latch portion 24a of the secondary latch 24 from its bearing engagement upon the half-round portion 31a of trip bar 31. Upon disengagement from its latched condition, secondary latch 24, under the spring bias of spring 30 exerted through linkage 2-4 and 27 as previously described, moves in a counterclockwise direction as shown in FIGURE 2.

Referring now to FIGURE 2, it will be seen that the secondary latch 24 has moved from its initial position of engagement (as shown by the dash-line outline) to a counterclockwise position where an extended portion of the secondary latch 24b is brought into engagement with the toggle link 20, collapsing the toggle linkage 20 and 21 upwardly against its spring bias and drawing the tripping member 15 to theleft in FIGURES 1 and 2 thereby disengaging the tripping member 15 from the primary latch 13 and permitting its spring bias to be overcome by the stronger spring bias of releasable member 12 which is released from its restrained engagement to actuate the main operating mechanism of the circuit breaker disengaging the main current carrying contracts thereof. Thus, the present invention is directed to an improved trip unit embodying a latching mechanism having collapsible toggle links which are spring biased in a straightened position of releasable engagement to collapsibly respond to current-sensitive means and effect the automatic interruption of overload currents through a multipole circuit breaker.

Referring again to FIGURE 1, the trip unit of the present invention also includes a manually operable and adjustable means for rele-asably tripping the latching mechanism of the trip unit so as to facilitate the removal and installation or replacement of such trip unit in a circuit breaker of the type concerning the invention. It will be appreciated by those skilled in the art, that multi pole circuit breakers of substantial current carrying capacity of the type previously described usually have a reciprocally operable and externally extending handle means which is movable to opposite positions to effect an on and off condition of the circuit breaker and such operation through the manual, externally extending handle means effects disengagement of the main current carrying contacts of the circuit breaker. Manually actuated disengagement of the main current carrying contact does not, however, trip the trip unit from its latched engagement with the main operating mechanism of the circuit breaker and more particularly with that particular member of the main operating mechanism such as the 4 releasable member 12 illustrated in FIGURES 1, 2 and 3. Accordingly, before a trip unit of this type can be removed, installed or replaced in a circuit breaker of.

the multipole type described, the latching mechanism must be released and disengaged from its state of latched engagement with main operating mechanism of the circuit breaker. It is highly desirable for such tripping operation to be readily accomplishable by means external of the trip unit. Such a means is shown in FIGURES l, 2 and 3.

Referring now to FIGURE 1, a lever 32 is illustrated as being supported for pivotal movement about the pivotal support 17 extending from the boss 18 of the casing 19 of the trip unit. The lever 32 extends downwardly and has a portion 32a disposed for engagement with the leg or L-shaped portion 20a of the toggle link 20. In its position of such engagement, the manually operable tripping lever 32 functions as a stop, restraining the toggle link 20 against collapsing downwardly. The manually operable trip lever 32 also includes a threaded means 33 carried by the lever 32 between its pivotal support 17 and its point of engagement with the Lshaped portion 20a of the toggle link 20. The threaded adjusting means 33 bears upon an extending portion 16a of the link 16, and by adjusting the disposition of the threaded means 33 in respect of its bearing upon 16a, the set straightened position of the toggle linkage comprising collapsible links 21 and 20 may be selectively established as desired. Thus, the manually operable trip unit of the present invention performs the additional functions of a stop for the collapsible toggle linkage with which it is associated and also provides a means for selectively adjusting the stop or set straightened posi-' tion of the associated toggle linkage. In operation, the manually operable trip lever 32 is moved in a counterclockwise direction so that its lower portion 32a bears upon the L-shaped leg 20a of toggle link 20, collapsing the toggle linkage 20 and 21 in an upward direction allowing the tripping member 15 to move inwardly away from the restraining engagement with the primary latch 13 so that the releasable member 12 of the main operating mechanism of the circuit breaker overcome-s the spring bias of primary latch 13 and is released from engagement with the primary latch 13, causing and permitting the main operating mechanism of the circuit breaker to disengage the main current carrying contacts thereof.

Referring now to FIGURE 3, this operation and actuation is illustrated in the manner in which is occurs by reason of movement of the manual tripping lever 32 in a counterclockwise direction. As is seen in FIGURE 3, the manually operable trip lever 3-2 has been moved in a counterclockwise direction from its position of FIG- URE 1, its lower end portion 32a has displaced the L- shaped leg 20a of the toggle link 20 to the right in a clockwise direction, upsetting and collapsing the toggle links 20 and 21 in an upward direction and drawing tripping member 15 out of restraining engagement with the primary latch 13, allowing the releasable member 12 of the main operating mechanism of the circuit breaker to disengage from its latched engagement with the primary latch 13 in the manner previously described. With the releasable member 12 released from its latched engagement with the latching mechanism of the trip unit of the circuit breaker, the spring bias and additional forces are relieved so that the trip unit of such a multipole circuit breaker may be replaced, removed or another trip unit of different calibration and rating may be installed in the multipole circuit breaker as desired.

Accordingly, the present invention in the form of an improved trip unit for multipole circuit breakers achieves the multiple functions of providing an externally operable manual trip means to release the latching mechanism of the trip unit, a stop means for spring biased members of the trip unit is provided and, further, means of adjusting the normal static or set position and calibrated disposition of such spring biased members is provided. Moreover, such additional multiple functions as I Patent of the United States is:

1. A trip unit adapted for removable mounting in a mult-ipole circuit breaker comprising: a casing enclosing said trip unit and having an" aperture therein; a tripping assembly mounted on said trip unit and including a collapsible toggle linkage positioned in said aperture and biased toward a set straightened position tor maintaining a tripping member in restraining engagement with a releasable means of said circuit breaker; said toggle linkage being collapsible upon the flow of overload currents of predetermined amplitude; pivoted lever means supported on said trip unit to engage a link of said toggle linkage, said lever being externally movable for opposing the bias of said toggle linkage andtor collapsing said linkage and releasing said releasable means; and means supported on said lever for adjusting the static disposition of said lever whereby to selectively establish the set straightened position of said toggle linkage.

2. A trip unit as claimed in claim 1 wherein said means for adjusting the static disposition of said lever is positioned between the pivotal support of said lever and its point of engagement with said toggle linkage.

3. A trip unit adapted for removable mounting in a multipole circuit breaker comprising: a casing enclosing said trip unit and having an aperture therein; a tripping assembly mounted on said ttrip unit and including two collapsible toggle links connected by a common pin, one of said toggle links having a stationary pivotal support and the other toggle link extending through said aperture and being biased in a set straightened position for maintaining a tripping member in restaining engagement with a releasable means of said circuit breaker; said toggle links being collapsible about said common pin upon the flow of overload currents; pivoted lever means supported on said trip unit to engage one of said toggle links, said lever being externally movable for opposing the bias of said toggle links and for collapsing said linkage and releasing said releasable means; and means supported on said lever for adjusting the static disposition of said lever whereby to selectively establish the set straightened position of said toggle linkage.

4. A trip unit adapted for removable mounting in a multi-pole circuit breaker comprising: a casing enclosing said trip unit and having an aperture therein; a tripping assembly mounted on said trip unit and including first and second toggle links connected by a common pin, said first toggle link having a stationary pivotal support, said second toggle having an L-shaped portion and extending through said aperture and being biased in a set straightened position for maintaining a tripping member in restraining engagement with a releasable member of said circuit breaker; said toggle links being collapsible about said common pin upon the flow of overload currents; pivoted lever means supported on said trip unit to engage said L-shaped .portion of said second toggle link, said lever being externally movable for displacing said L shaped toggle link and for collapsing said toggle links about their common pin and releasing said releasable means; and means supported on said lever for adjusting the static disposition of said lever whereby to selectively establish the set straightened position of said toggle linkage.

5. A trip unit as claimed in claim 4 wherein said means supported on said lever for adjusting the set straightened position of said toggle linkage comprises a screw threadedly received therethrough and aligned to bear upon means supported by said trip unit.

6. A multiple electric circuit breaker comprising: a main insulating casing; at least two pairs of relatively movable contacts supported in said casing; a member releasable to cause automatic opening of said contacts; a

primary latch disposed and arranged to releasably engage said releasble member; a separately enclosed trip uni-t removably mountedin said main insulating casing; a tripping member pivotally supported on said trip unit and positionable for engagement with said primary latch; a collapsible toggle linkage connected with said tripping member and biased in set straightened position for maintaining said tripping member in restraining engagement with said primary latch; said toggle linkage being collapsible upon the flow of overload currents of predetermined amplitude through said circuit breaker; lever means supported externally on said trip unit and having a portion disposed to engage-said toggle linkage, said lever being movable for opposing the bias of said toggle linkage to collapse said toggle linkage and release said tripping member from restraining engagement with said toggle linkage whereby to selectively establish the set straightened position of said toggle linkage.

7. A multipole electric circuit breaker comprising: a main insulating casing; at least two pairs of relatively movable contacts supported in said casing; a member releasable to cause automatic opening of said contacts; a primary latch disposed and arranged to releasably engage said releasable member; a separately enclosed trip unit removably mounted in said main insulating casing; a tripping member pivotally supported on said separately enclosed trip unit and positionable for engagement with said primary latch, a pair of collapsible toggle links having a comm-on pin connection and one end connected to said tripping member, said toggle links being biased in set straightened position for maintaining said tripping member inrestraining engagement with said primary latch; said toggle links being collapsible upon the flow of overload currents of predetermined amplitude through said circuit breaker; lever means supported on said separately enclosed trip unit to engage one of said toggle links, said lever being externally movable for opposing the bias of said toggle links to collapse said linkage and release said tripping member from restraining engagement with said primary latch, and a threaded means carried by said lever and positioned to be engageable with said tripping member pivotal support for adjusting the static position of en-gatg ment of said lever with said toggle link, whereby to selectively establish the set straightened position of said toggle linkage.

References Cited by the Applicant UNITED STATES PATENTS 1,391,469 9/ 1921 Getchell. 1,657,688 1/ 1928 Scott. 2,349,631 5/ 1944 Lindstrom et al. 2,359,139 9/1944 May et a1.

BERNARD A. GILHEANY, Primary Examiner.

H. B. GILSON, Assistant Examiner. 

1. A TRIP UNIT ADAPTED FOR REMOVABLE MOUNTING IN A MULTIPOLE CIRCUIT BREAKER COMPRISING: A CASING ENCLOSING SAID TRIP UNIT AND HAVING AN APERTURE THEREIN; A TRIPPING ASSEMBLY MOUNTED ON SAID TRIP UNIT AND INCLUDING A COLLAPSIBLE TOGGLE LINKAGE POSITIONED IN SAID APERTURE AND BIASED TOWARD A SET STRAIGHTENED POSITION FOR MAINTAINING A TRIPPING MEMBER IN RESTRAINING ENGAGEMENT WITH A RELEASABLE MEANS TO SAID CIRCUIT BREAKER; SAID TOGGLE LINKAGE BEING COLLAPSIBLE UPON THE FLOW OF OVERLOAD CURRENTS OF PREDETERMINED AMPLITUDE; PIVOTED LEVER MEANS SUPPORTED ON SAID TRIP UNIT TO ENGAGE A LINK OF SAID TOGGLE LINKAGE, SAID LEVER BEING EXTERNALLY MOVABLE FOR OPPOSING THE BIAS OF SAID TOGGLE LINKAGE AND FOR COLLAPSING SAID LINKAGE AND RELEASING SAID RELEASABLE MEANS; AND MEANS SUPPORTED ON SAID LEVER FOR ADJUSTING THE STATIC DISPOSITION OF SAID LEVER WHEREBY TO SELECTIVELY ESTABLISH THE SET STRAIGHTENED POSITION OF SAID TOGGLE LINKAGE. 